1. Technical Field
The present invention relates to a technique for eliminating clogging of a nozzle in a liquid ejection apparatus for ejecting fluid.
2. Related Art
In an ink jet type recording apparatus, ink is ejected on a recording paper or the like via a nozzle. Accordingly, there was a fear that ejection of ink can not be performed well due to clogging of the nozzle caused by increase of the viscosity of the ink near the nozzle or incorporation of bubbles in the nozzle. Consequently, an ink jet type recording apparatus that suctions and removes bubbles and viscosity increased ink remained in the nozzle by covering an ejection surface of the head with a dedicated cap and applying a negative pressure in the cap (hereinafter, referred to as “suction recovery processing”) has been proposed (see JP-A-2003-334962).
In the aforementioned ink jet type recording apparatus, the ink ejected by the suction recovery processing may be adhered to the ejection surface of the head. Consequently, a wiper is provided near the dedicated cap and wiping the ink drop adhered to the ejection surface by scraping (wiping) the ejection surface with the wiper in some of the ink jet type recording apparatus. In such an ink jet recording apparatus, the ink wiped from the ejection surface when wiped may be adhered to the boundary portion between the ejection surface (nozzle plate) and a head side surface and to a head cover disposed at the boundary portion. In this case, the ink adhered to the head cover and the like is dried and the viscosity thereof is increased in, for example, a power source off state and a print standby state. As a result, there is a fear that the viscosity increased ink is adhered to the wiper when wiped at the next time and the viscosity increased ink is applied on the ejection surface. In this case, the nozzle on which the viscosity increased ink is applied may be clogged to cause ejection error of ink.
Note that the aforementioned problem may also occur in an ink jet type recording apparatus that is not equipped with a wiper. For example, in the case where a printing paper is made contact with the ejection surface of the head due to curling or folding of the printing paper, there is a fear that the viscosity increased ink adhered to a head cover and the like is applied on the ejection surface by the printing paper. Further, also in an ink jet type recording apparatus that performs so called flushing operation for removing viscosity increased ink and the like by ejecting a predetermined amount of ink from all of nozzles, the ink ejected by the flushing operation may be adhered to a head ejection surface to cause the aforementioned problem. That is, the aforementioned problem may occur in an ink jet type recording apparatus that performs a processing for ejecting ink from each nozzle separately from print processing (hereinafter, referred to as “preliminary ejection process”). Further, the aforementioned problem may occur in not only the ink jet type recording apparatus, but also in a fluid ejection apparatus that ejects another fluid except ink (including liquid, liquid material in which particles of a functional material are dispersed, solid such as a powder that can be ejected as liquid).